Porous materials have a comparatively large specific surface area, and thus can adsorb large quantities of gas or small organic molecules. Such porous materials may be useful for applications including gas storage, gas separation, ion transport membranes and, in general, applications where trapping or transporting a chemical entity through a material is required. Additionally, porous materials may be useful for other applications, such as dielectrics, novel composites (e.g. P/R, fusing, drug release), supercapacitors, or catalysis. Most permanently porous materials are usually inorganic compounds, obtained as refractory powders that need to be imbedded into other materials to create films so they can be appropriated for device integration (e.g. electronics, fuel cells, batteries, gas separation membranes, etc.).
Typical porous materials comprise microporous materials having pore size less than 2 nm, mesoporous materials having pore size between 2 nm and 50 nm, and macroporous materials having pore size bigger than 50 nm. In 1995, Omar Yaghi synthesized the MOF (metal-organic-framework) (referring to Nature, 1995, (378), 703), a metal-organic coordination polymer that is really close to practical application. As a new functional molecular material, the MOF not only has a crystal structure similar to the zeolite molecular sieve, but also its structure is capable of being designed. The MOF can obtain nano-size pore channels and cavities by directionally designing the topological structure and expanding the organic functional groups. However, the MOF has a comparative poor chemical stability. In 2005, Omar Yaghi disclosed the COF (covalent organic framework) (referring to Science, 2005, (310), 1166), an organic porous framework material, which is composed of light elements (C, H, O, B) being connected via covalent bonds. However, the chemical stability problem is not really solved.
COFs, differ from polymers/cross-linked polymers in that COFs are intended to be highly patterned. In COF chemistry molecular components are called molecular building blocks rather than monomers. During COF synthesis molecular building blocks react to form two- or three-dimensional networks. Consequently, molecular building blocks are patterned throughout COF materials and molecular building blocks are linked to each other through strong covalent bonds.
COFs developed thus far are typically powders with high porosity and are materials with exceptionally low density. COFs can store near-record amounts of argon and nitrogen. While these conventional COFs are useful, there is a need, addressed by embodiments of the present invention, for new materials that offer advantages over conventional COFs in terms of enhanced characteristics.
The properties and characteristics of conventional COFs are described in the following documents:    Yaghi et al., U.S. Pat. No. 7,582,798;    Yaghi et al., U.S. Pat. No. 7,196,210;    Shun Wan et al., “A Belt-Shaped, Blue Luminescent, and Semiconducting Covalent Organic Framework,” Angew. Chem. Int. Ed., Vol. 47, pp. 8826-8830 (published on web Jan. 10, 2008);    Nikolas A. A. Zwaneveld et al., “Organized Formation of 2D Extended Covalent Organic Frameworks at Surfaces,” J. Am. Chem. Soc., Vol. 130, pp. 6678-6679 (published on web Apr. 30, 2008);    Adrien P. Cote et al., “Porous, Crystalline, Covalent Organic Frameworks,” Science, Vol. 310, pp. 1166-1170 (Nov. 18, 2005);    Hani El-Kaderi et al., “Designed Synthesis of 3D Covalent Organic Frameworks,” Science, Vol. 316, pp. 268-272 (Apr. 13, 2007);    Adrien P. Cote et al., “Reticular Synthesis of Microporous and Mesoporous Covalent Organic Frameworks” J. Am. Chem. Soc., Vol. 129, 12914-12915 (published on web Oct. 6, 2007);    Omar M. Yaghi et al., “Reticular synthesis and the design of new materials,” Nature, Vol. 423, pp. 705-714 (Jun. 12, 2003);    Nathan W. Ockwig et al., “Reticular Chemistry: Occurrence and Taxonomy of Nets and Grammar for the Design of Frameworks,” Acc. Chem. Res., Vol. 38, No. 3, pp. 176-182 (published on web Jan. 19, 2005);    Pierre Kuhn et al., ‘Porous, Covalent Triazine-Based Frameworks Prepared by Ionothermal Synthesis,” Angew. Chem. Int. Ed., Vol. 47, pp. 3450-3453. (Published on web Mar. 10, 2008);    Jia-Xing Jiang et al., “Conjugated Microporous Poly(aryleneethylnylene) Networks,” Angew. Chem. Int. Ed., Vol. 46, (2008) pp, 1-5 (Published on web Sep. 26, 2008);    Hunt, J. R. et al. “Reticular Synthesis of Covalent-Organic Borosilicate Frameworks” J. Am. Chem. Soc., Vol. 130, (2008), 11872-11873. (published on web Aug. 16, 2008); and    Colson et al. “Oriented 2D Covalent Organic Framework Thin Films on Single-Layer” Science, 332, 228-231 (2011).
Gas storage materials that are being developed are currently powders that need to be compacted or shaped and subsequently inserted into cylindrical containers for use. Considerable benefit in optimizing the storage system geometry and footprint can be accessed if the gas storage material were in a form other than a powder, such as a film. Thus, improvements are still needed over the conventional porous materials.